Spark plug comprising a ground electrode support

Abstract

The invention relates to a spark plug of an internal combustion engine, especially for use in Otto gas engines. Said spark plug comprises, supported by an insulating body ( 1 ), a preferably one-piece spark plug shell ( 2 ) and a center electrode ( 3 ), which is especially rod-shaped or has a plurality of electrode fingers, and at least one ground electrode ( 4 ), preferably a plurality of ground electrodes, the center electrode ( 3 ) and the at least one ground electrode ( 4 ) being surrounded by a chamber, especially a pre-chamber ( 5 a ) or a swirl chamber ( 5 b ) supported by the spark plug shell ( 2 ), or being located inside said chamber ( 5 a, 5 b ). The invention is characterized in that the ground electrode(s) ( 4 ) has/have a support ( 6 ) secured to the spark plug shell ( 2 ) or arranged thereon as the base, or branch(es) off therefrom, and in that said ground electrode support ( 6 ) and every finger-type ground electrode ( 4 ) branching off therefrom is arranged at a distance ( 21 ) from the inner wall surface ( 7 ) of the chamber ( 5 a, 5 b ).

1. A spark plug for an internal combustion engine, comprising:
 a spark plug shell and an insulating body carrying said spark plug shell; 
 a center electrode and at least one ground electrode disposed on said spark plug shell; 
 said center electrode and said at least one ground electrode being encased by a chamber supported on said spark plug shell, and disposed within said chamber; 
 a wall part of said chamber having a circular-ring-shaped cross section or being formed from a cylindrical ring; 
 said at least one ground electrode having a support disposed on said spark plug shell and extending from said support; and 
 said ground electrode support and each said at least one ground electrode extending therefrom being disposed at a spacing distance from an inner wall surface of said chamber; 
 said ground electrode support having a circular-ring-shaped cross section viewed perpendicular to a longitudinal axis of the spark plug, or being formed by a cylindrical ring; 
 two concentric, cylindrical end projections formed on said spark plug shell, said end projections including an inner end projection extending above an outer end projection in a direction of said chamber; and 
 wherein said ground electrode support is placed on said inner end projection, and said wall part of said chamber is placed on said outer end projection. 
 
     
     
       2. The spark plug according to  claim 1 , configured for an Otto-cycle gasoline engine. 
     
     
       3. The spark plug according to  claim 1 , wherein said spark plug shell is a one-piece housing. 
     
     
       4. The spark plug according to  claim 1 , wherein said center electrode is a rod-shaped or multi-fingered center electrode. 
     
     
       5. The spark plug according to  claim 1 , wherein said chamber is formed as a pre-chamber or as a swirl chamber. 
     
     
       6. The spark plug according to  claim 5 , wherein said swirl chamber is open on a combustion chamber side, or said pre-chamber surrounds said at least one ground electrode close to the shell. 
     
     
       7. The spark plug according to  claim 1 , wherein ground electrode support and said wall part of said chamber are set, placed, or screwed, or attached on said inner end projection and on said outer end projection, respectively. 
     
     
       8. The spark plug according to  claim 1 , wherein said at least one ground electrode and the corresponding said support are integrally formed as one piece or joined to one another by welding. 
     
     
       9. The spark plug according to  claim 1 , which comprises a cylinder ring inserted between said wall part and said ground electrode support, and when the spark plug is in operation, said ring adjoining the inner wall surface of said wall part and an outer surface of said ground electrode support. 
     
     
       10. The spark plug according to  claim 5 , which comprises an end wall supported by said cylindrical wall part of said pre-chamber, said end wall delimiting an inner space of said pre-chamber or being configured as one piece with said wall part, and wherein at least one of said wall part and said end wall has through-openings formed therein to permit ignited gas jets to pass through. 
     
     
       11. The spark plug according to  claim 10 , wherein said end wall is planar or cupola-shaped. 
     
     
       12. The spark plug according to  claim 1 , wherein said ground electrode support supports a number of one, three, or five ground electrodes distributed about said center electrode equidistant and at equal intervals, wherein each of said finger-shaped ground electrodes projecting out from said ground electrode support has a rectangular or cylindrical-ring-shaped cross section transverse to a longitudinal extension at least in partial segments thereof. 
     
     
       13. The spark plug according to  claim 12 , wherein at least one, or each, of said ground electrode(s) extends from said support in the form of a finger and an end area on a combustion chamber side extends parallel to the longitudinal axis or to the facing surface area of said center electrode, and wherein a spark gap is formed between surface areas of said ground electrode and said center electrode opposite one another and extending parallel to the longitudinal axis. 
     
     
       14. The spark plug according to  claim 1 , wherein the wall part of said chamber has at least one rinsing recess or opening formed therein for passage of a fuel-air mixture and at least one recess configured to expose a combustion-chamber-side end area of said finger-shaped ground electrodes placed opposite the particular said end area. 
     
     
       15. The spark plug according to  claim 13 , wherein said at least one rinsing recess or opening has a circular cross section, and said recess is a slitshaped recess. 
     
     
       16. The spark plug according to  claim 1 , wherein an outer thread is formed on each of the concentrically placed end projections, and an inner thread adapted to said outer thread is formed on the inner wall surface of said wall part of said chamber and on the inner wall surface of said support, said ground electrode support and said cylindrical-ring-shaped wall part of said chamber are disposed concentrically to each other while forming the pre-set interval and/or that the cylindrical wall part and the support are placed on the particular projection and attached there by welding. 
     
     
       17. The spark plug according to  claim 1 , wherein a spacing distance between an outer surface of said ground electrode support and said wall part of said chamber is smaller than a thickness of said wall part of said chamber, and wherein a thickness of said ground electrode support is three to fifteen times a width of the spark gap, and/or wherein a spacing distance between said outer wall surface of said ground electrode support and said inner wall surface of said chamber is 50 to 200% of a width of the spark gap. 
     
     
       18. The spark plug according to  claim 17 , wherein the thickness of said ground electrode support is five to ten times the width of the spark gap. 
     
     
       19. The spark plug according to  claim 1 , which comprises a precious metal alloy or at least a platelet made of precious metal alloy disposed on circumferential areas or on locally limited elevations or on radial surface areas pointing toward said center electrode and/or on a surface of said finger-shaped ground electrode facing said center electrode, or on elevations configured on said surface, in strips that lie next to each other. 
     
     
       20. The spark plug according to  claim 19 , wherein said precious metal alloy or said platelet of precious metal alloy is applied or fused or welded on, and said strips lie next to each other and on top of one another. 
     
     
       21. The spark plug according to  claim 1 , wherein said center electrode is shaped as a compact component or as a quiver-shaped component filled with a material having high thermal conductivity and slid onto a center electrode base and welded thereto. 
     
     
       22. The spark plug according to  claim 1 , wherein an end of said wall part of a swirl chamber on the combustion chamber side projects over a side of said center electrode and/or the ground electrodes on the combustion chamber side, and wherein, said wall part of said chamber, opposite each said ground electrode, is formed with a slot extending parallel to said ground electrode. 
     
     
       23. The spark plug according to  claim 22 , wherein said slot extending parallel to said ground electrode is open to the end of said wall part on the combustion chamber side, providing access to the end area of said ground electrode. 
     
     
       24. The spark plug according to  claim 1 , wherein said wall part of said chamber and said support are electrical conductors, and are connected so as to conduct electricity with the spark plug shell and wherein each finger-shaped ground electrode is bent from its respective said support in a direction toward said center electrode and after a further bend, runs in a direction substantially parallel to said center electrode. 
     
     
       25. The spark plug according to  claim 24 , wherein at least one of said wall part of said chamber, a sheathing of said center electrode, and said at least one ground electrode with the support thereof is formed of one of a nickel-based alloy, a high-temperature steel, and hot-corrosion-resistant metal alloys with good thermal conductivity capabilities, and wherein said pre-chamber is formed of brass.